Lens driving apparatus

ABSTRACT

Disclosed is a lens driving apparatus. The lens driving apparatus includes a base, a yoke coupled to the base, having an upper surface formed with a hole, a closed side surface, and an opened bottom surface, a bobbin movably installed in an inner portion of the yoke, a lens module coupled to the bobbin to go in and out the hole according to movement of the bobbin, a magnet fixed to an inner portion of the yoke, a coil fixed to an outer portion of the bobbin while facing the magnets, and springs coupled to the bobbin to provide restoration force to the bobbin.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/516,146, filed May 22, 2009, now U.S. Pat. No. 7,885,023, issued Feb.8, 2011, which is the U.S. national stage application of InternationalPatent Application No. PCT/KR2007/005901, filed Nov. 22, 2007, whichclaims priority to Korean Patent Application No. 10-2006-0116317, filedNov. 23, 2006, all of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present invention relates to a lens driving apparatus.

BACKGROUND ART

Recently, as electronic appliances have multi-functions, variouselectronic appliances having cameras therein, such as MP3 players,mobile communication terminals and PDAs, have been widely used.

As electronic appliances having cameras therein are manufactured in asmall size, parts for providing camera functions must also bemanufactured in a small size.

Further, since electronic appliances having cameras therein may beeasily exposed to external environment or impact in terms of thecharacteristics of portable electronic appliances, external impuritiesmay easily penetrate into the electronic appliances or the electronicappliances may be easily broken by the impact.

Technical Problem

The embodiment provides a lens driving apparatus which can be designedin a simple structure and manufactured in a small size. The embodimentprovides a lens driving apparatus having high resistance against impactand preventing penetration of external impurities.

Technical Solution

A lens driving apparatus according to an embodiment comprising: a base;a yoke coupled to the base, having an upper surface formed with a hole,a closed side surface, and an opened bottom surface; a bobbin movablyinstalled in an inner portion of the yoke; a lens module coupled to thebobbin to go in and out the hole according to movement of the bobbin; amagnet fixed to an inner portion of the yoke; a coil fixed to an outerportion of the bobbin while facing the magnets; and springs coupled tothe bobbin to provide restoration force to the bobbin.

Advantageous Effects

According to the lens driving apparatus of the embodiment, a yoke isdirectly coupled to a base and parts are installed in a space formed inan inner portion of the base and the yoke. Accordingly, since anadditional case is not necessary, the number of parts is reduced, anassembly procedure is simplified, and thus the manufacturing cost can besaved. Further, according to the lens driving apparatus of theembodiment, the base is coupled to the yoke while maintaining a sealingstatus by locking holes of the base and locking protrusions of the yoke.That is, any gap does not exist in the sides of the base and the yoke, ahole of the yoke is shielded by a lens module, and a through hole of thebase is closely coupled to an electronic appliance, so that impuritiescan be prevented from penetrating into the inner space formed be thebase and the yoke. As a result, the parts are not damaged by theimpurities. Furthermore, when a prism magnet is used, since themanufacturing cost is saved as compared with a case of using aring-shaped magnet, the economical efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing a lens driving apparatusaccording to the embodiment;

FIG. 2 is a sectional view showing the lens driving apparatus in FIG. 1;

FIG. 3 is a perspective view showing a state in which a magnet and acoil are installed at the yoke in FIG. 1; and

FIG. 4 is a perspective view showing a coupling state of the yoke andthe base in FIG. 1.

MODE FOR THE INVENTION

Hereinafter, a lens driving apparatus according to an embodiment will bedescribed with reference to accompanying drawings. FIG. 1 is an explodedperspective view showing the lens driving apparatus according to theembodiment, FIG. 2 is a sectional view showing the lens drivingapparatus in FIG. 1, and FIG. 3 is a perspective view showing a state inwhich a magnet and a coil are installed at the yoke in FIG. 1.

As shown in FIGS. 1 and 2, the lens driving apparatus according to theembodiment comprises a base 110 and a metal yoke 120 which are coupledto each other to form a predetermined space.

The base 110 has a disc shape or a polygonal plate shape and is formedat the central portion thereof with a through hole 111. The bottomsurface of the base 110 is coupled to an electronic appliance (notshown) and a circuit substrate 112 provided with an image sensor (notshown) is arranged in the through hole 111.

The yoke 120 is coupled to the base 110 to serve as a case forprotecting parts. The yoke 120 has an upper surface, at which a hole 121allowing entrance of a lens module 200 is formed, an opened bottomsurface making contact with the upper surface of the base 110, andclosed lateral side surfaces.

The side surfaces of the lens driving apparatus according to theembodiment are closed by the base 110 and the yoke 120. Accordingly,since an additional case for protecting the lens driving apparatus isnot necessary, the structure of the lens driving apparatus can besimplified. Further, since the side surfaces of the lens drivingapparatus are closed, external impurities cannot penetrate into theinner side of the lens driving apparatus.

A ring-shaped bobbin 130 that goes in and out the hole 121 is movablyinstalled at the inner side of the yoke 120. The lens module 200provided with a lens 202 and a support 201 for supporting the lens 202is coupled to the inner peripheral surface of the bobbin 130.

The bobbin 130 includes an outer surface having a circular or apolygonal shape corresponding to the yoke 120, and an inner surfacehaving a circular shape corresponding to the outer surface of the lensmodule 200. According to the embodiment, the bobbin 130 includes anouter surface having an octagonal shape.

Magnets 140 are fixed to the inner peripheral surface of the yoke 120,and a coil 150 is wound around the outer peripheral surface of thebobbin 130 while facing the magnets 140.

The magnet 140 has a circular or a polygonal shape corresponding to theyoke 120. As shown in FIGS. 1 and 3, when the yoke 120 is a polygonalcase, a plurality of prism magnets 140 are prepared and three sides ofeach magnet 140 make contact with the inner peripheral surface of theyoke 120.

In the lens driving apparatus according to the embodiment, since themagnets 140 are installed at four edges of the yoke 120, respectively,an empty space between the yoke 120 and the coil 150 can be effectivelyutilized. Accordingly, the lens driving apparatus can be manufactured ina smaller size. Further, since the prism magnet 140 is inexpensive ascompared with a ring-shaped magnet, the lens driving apparatus with alow price can be manufactured.

Since the coil 150 is wound around the outer peripheral surface of thebobbin 130, the coil 150 has a circular or a polygonal shapecorresponding to the outer surface of the bobbin 130. If the coil 150has a polygonal shape and the magnet 140 has a circular shape, thedistance between the coil 150 and the magnet 140 becomes non-uniform.

Accordingly, when the coil 150 has a polygonal shape, the magnet 140 hasa prism shape as shown in FIGS. 1 and 3.

As electric current is applied to the coil 150, the coil 150 movesupward according to the interaction of the electric field generated bythe coil 150 and the magnetic field generated by the magnet 140, andthus the bobbin 130 moves upward. Accordingly, the lens module 200coupled to the bobbin 130 also moves upward.

In addition, if the electric current is not applied to the coil 150, thebobbin 130 moves downward. To this end, upper and lower leaf springs 161and 165 having a coil structure are installed at the upper and lowerportions of the bobbin 130 in order to provide restoration force forreturning the bobbin 130 to the initial state.

At this time, the outer portion of the upper spring 161 is insertedbetween the yoke 120 and the upper surface of the magnet 140. Further,the inner portion of the upper spring 161 is inserted into first supportprotrusions 131 formed on the upper end surface of the bobbin 130.Accordingly, the upper spring 161 can be prevented from being rotatedand moved due to external impact.

The inner portion of the lower spring 165 is integrally formed with thebobbin 130 through injection molding, and the outer portion of the lowerspring 165 is inserted between the bottom surface of a spacer 170 andthe base 110. Further, second support protrusions 133 that make contactwith the inner peripheral surface of the through hole 110 formed in thebase 110 are formed on the lower end surface of the bobbin 130. Thesecond support protrusions 133 guide and support the bobbin 130 suchthat the bobbin 130 can be coupled to another element at an exactposition and exactly move upward and downward.

The spacer 170 is installed at the base 110 below the magnets 140 andthe outer surface of the lower spring 165 is inserted between the lowersurface of the spacer 170 and the base 110. That is, the outer portionof the lower spring 165 is supported between the spacer 170 and the base110, and the inner portion of the lower spring 165 is integrally formedwith the bobbin 130, so that the lower spring 165 can be prevented frombeing rotated and moved due to external impact.

Further, the spacer 170 has insertion protrusions 171 used for firmcoupling and movement prevention of the spacer 170, and the base 110 hassupport holes 173 into which the insertion protrusions 171 are inserted.

The yoke 120 and the spacer 170 have step sections 120 a and 170 a,respectively, as shown in FIG. 2. The step sections 120 a and 170 aprovide a space for movement of the middle parts of the upper and lowerleaf springs 161 and 165.

Hereinafter, a coupling structure of the base 110 and the yoke 120 willbe described with reference to FIGS. 1, 2 and 4.

FIG. 4 is a perspective view showing a coupling state of the yoke andthe base in FIG. 1.

As shown in FIG. 4, the base 110 has a plurality of protrusion plates115 protruding upward on the outer surface thereof, and lockingprotrusions 117 are formed at the protrusion plates 115, respectively.Further, the yoke 120 has locking holes 127 at the sides thereof, intowhich the locking protrusions 117 are inserted.

The base 110 is closely coupled to the yoke 120 by using the lockingprotrusions 117 and the locking holes 127.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure.

INDUSTRIAL APPLICABILITY

The lens driving apparatus according to the embodiment can bemanufactured in a small size, can prevent external impurities frompenetrating into the inner portion of the lens driving apparatus, and isnot broken due to external impact.

Further, the lens driving apparatus according to the embodiment can beapplied to both cameras and various electronic appliances provided withthe cameras.

What is claimed is:
 1. A lens driving apparatus comprising: a base; ayoke coupled to the base; a bobbin movably disposed in an inner portionof the yoke; magnets disposed in the yoke; a coil fixed to an outerportion of the bobbin while facing the magnets; and springs coupled tothe bobbin to provide restoration force to the bobbin, wherein thesprings comprise an upper spring coupled to an upper portion of thebobbin and a lower spring coupled to a lower portion of the bobbin,wherein the coil has an octagonal shape, and wherein the upper springhas a first side, which is disposed between the yoke and the magnets,and a second side coupled to the bobbin.
 2. The lens driving apparatusas claimed in claim 1, wherein the base has locking protrusions and theyoke has locking holes into which the locking protrusions are inserted.3. The lens driving apparatus as claimed in claim 1, wherein sidesurfaces of the lens driving apparatus are closed by the base and theyoke.
 4. The lens driving apparatus as claimed in claim 1, wherein thesecond side of the upper spring is inserted into first supportprotrusions formed at the upper portion of the bobbin.
 5. The lensdriving apparatus as claimed in claim 1, further comprising: a lensmodule coupled to the bobbin to go in and out a hole of the yokeaccording to movement of the bobbin.
 6. The lens driving apparatus asclaimed in claim 1, wherein the yoke includes an upper surface formedwith a hole, a closed side surface, and an opened bottom surface.
 7. Thelens driving apparatus as claimed in claim 1, wherein the magnet isfixed to an inner portion of the yoke.
 8. The lens driving apparatus asclaimed in claim 1, wherein the lower spring has one side integrallyformed with the bobbin through injection molding.
 9. The lens drivingapparatus as claimed in claim 1, wherein a side surface of the bobbinhas an octagonal shape.
 10. A lens driving apparatus comprising: a base;a yoke coupled to the base; a bobbin movably disposed in an innerportion of the yoke; magnets disposed in the yoke; a coil fixed to anouter portion of the bobbin while facing the magnets; and springscoupled to the bobbin to provide restoration force to the bobbin,wherein the springs comprise an upper spring coupled to an upper portionof the bobbin and a lower spring coupled to a lower portion of thebobbin, wherein the yoke is disposed on an outermost surface of the lensdriving apparatus, and wherein the coil is overlapped with the yoke in ahorizontal plane and wherein the coil is not overlapped with the yoke ina vertical plane.
 11. The lens driving apparatus as claimed in claim 10,wherein a portion of the bobbin between an upper surface and a sidesurface of the bobbin is exposed to an outside.
 12. The lens drivingapparatus as claimed in claim 10, wherein the upper spring is disposedbetween the yoke and the magnets.